Anticoccidial composition

ABSTRACT

Compositions comprising a mixture of a 2,4-diamino-5-(trisubstituted)benzyl-pyrimidine potentiated sulfonamide antibiotic with an ionophorous polyether anticoccidial agent are useful for the treatment and prevention of coccidiosis in animals.

BACKGROUND OF THE INVENTION

This invention relates to compositions useful for the prevention andtreatment of coccidiosis in animals, methods of using the compositionsand animal comestibles containing the compositions.

Coccidiosis is a troublesome disease which afflicts animals such ascompanion animals and ranch or farm animals raised commercially as afood source. The disease is caused by protozoal parasites calledcoccidia, which belong to the genus Eimeria. Typically, the infectionoccurs when the animal ingests food, water or fecal materialcontaminated with Eimeria organisms in the sporulated oocyst stage andthe ingested oocysts enter the intestine and the cecum. The infectionresults in the destruction of the intestinal linings of the host animal,often leading to death. Even if the animals survive the infection, theygrow more slowly than normal and the feed efficiency is adverselyaffected, causing significant economic losses if the infection involveslarge populations of food animals such as chickens, turkeys, geese,ducks, cattle, sheep and pigs.

Coccidiostatic agents are available for the prevention or treatment ofcoccidiosis. However, many of these agents are not entirely satisfactoryin maintaining feed efficiency and weight gain, and others have verynarrow safety and efficacy ranges and thus pose a risk to the animalsbeing treated. Moreover, to a greater extent Eimeria organisms aredeveloping resistance to the more frequently used coccidiostatic agentsavailable on the market, thus limiting the effectiveness of such agents.

A widely used commercially available class of coccidiostats are thosebelonging to the group of polyether antibiotics isolated from variousstrains of bacteria. These substances are characterized by cyclic ethermoieties in their chemical structures and are also commonly referred toas "ionophores" because of what is believed to be theirtransport-inducing mode of action. Among the more notable examples arelasalocid, monensin, salinomycin, lonomycin, narasin and maduramycin.

Non-ionophorous anticoccidial agents include those based on combinationsof a sulfanilamide antibiotic and a potentiating2,4-diamino-5-(2',4',5'-trisubstituted benzyl) pyrimidine. Combinationsof this type are described in U.S. Pat. No. 3,461,206 (Hoffer andMitrovic).

Potentiated sulfanilamides have experienced limited commercial use asanticoccidials due to their more moderate effectiveness compared toionophores. Ionophorous anticoccidials, while possessing very goodcoccidiocidal activity as a class often pose difficulties in use becauseof their relatively narrow range of efficacy and the development ofresistance to them.

SUMMARY OF THE INVENTION

The discovery has now been made that compositions containing acombination of (1) a potentiated sulfonamide and (2) an ionophoreanticoccidial result in significantly enhanced activity againstcoccidiosis in animals caused by Eimeria organisms, especiallyionophore-resistant strains. The anticoccidial activity of the presentcompositions against ionophore-resistant strains is greater than wouldbe expected from a mere additive effect of the components.

Briefly, the present invention provides compositions containing theabove mentioned active ingredients which are useful for the preventionand treatment of coccidiosis in animals. Additionally, the presentinvention includes a method for combating coccidiosis in animals,especially poultry, by orally administering the described compositions.Still further, this invention comprises animal comestibles and feedpremixes containing the described compositions.

DETAILED DESCRIPTION OF THE INVENTION

The compositions of the present invention, when administered to animalssuch as companion animals (dogs, cats, etc.) and to animals raisedcommercially for food (poultry, cattle, sheep, pigs, etc.), areeffective in the prophylaxis and treatment of coccidiosis. As has beendiscussed, the potentiated sulfonamide beneficially and synergisticallyinteracts with the ionophorous component in the present compositions,resulting in greater activity against coccidiosis-causing strains ofEimeria. Because of their potentiated activity, these compositions areespecially useful against virulent ionophore-resistant strains ofEimeria, including those comprising the coccidiosis-producing organismswhich afflict poultry, such as E. tenella, E. maxima and E. acervulina.The present invention also makes possible the use of reduced amounts ofthe ionophorous component, thus lessening the risks normally associatedwith the utilization of many of these anticoccidial agents, such astoxicity and the concomitant effects on water intake, feeding patternand nutrient absorption.

The sulfonamides are a known class of antibiotics which arecharacterized by the radical --SO₂ NH₂. Suitable sulfonamides for thesecompositions are any of those that when combined with the describedpotentiator are useful in combating coccidiosis in animals, includingthe sulfonamides described in the previously mentioned U.S. Pat. No.3,461,206.

Preferred for use in the practice of this invention aresulfadimethoxine, sulfamethoxazole, sulfadiazine and sulfadimethazine,especially sulfadimethoxine.

These sulfonamides are employed in the present compositions inconjunction with a potentiator of their activity, namely a substitutedpyrimidine potentiator, and more specifically a2,4-diamino-5-(trisubstituted)benzylpyrimidine sulfonamide potentiatorof the formula ##STR1## in which R is methoxy, methyl or ethyl.

Exemplary of suitable compounds within the above formula which areuseful in the present compositions as potentiators for the sulfonamideare the following:

2,4-diamino-5-(2',4',5'-trimethoxybenzyl)pyrimidine (trimethoprim)

2,4-diamino-5-(2'-methyl-4',5'-dimethoxybenzyl)pyrimidine (ormetoprim)

2,4-diamino-5-(2'-ethyl-4,5'-dimethoxybenzyl)pyrimidine

Especially preferred for use in the present compositions arecombinations of sulfadimethoxine and ormetoprim.

The 2,4-diamino-5-(trisubstituted)benzyl-pyrimidine potentiator isgenerally employed in these compositions in amounts ranging from about0.01 to about 20 parts by weights for each part by weight of thesulfonamide. More effectively, however, the weight ratio of thesulfonamide to the 2,4-diamino-5-(trisubstituted)benzyl-pyrimidine inthe compositions is in the range from about 20:1 to about 1:1, withespecially efficacious results being obtained using weight ratios ofabout 5:3 or about 5:1 (about 5:3 being the most favored).

As previously mentioned, the compositions of this invention also containas an additional active ingredient the ionophore, which can be in theform of the antibiotic or its pharmaceutically acceptable salt or ester.The ionophore (polyether) component of these compositions can be any ofthe known anticoccidial ionophores such as, for example, lasalocid,monensin, maduramycin, narasin, nigericin, lonomycin, dianemycin andsalinomycin, as well as the trimethylene glycyl ether of maduramycin.Still other ionophores useful as anticoccidials in the presentcompositions will occur to those skilled in the art from disclosure ofsuch agents in the literature, for instance, Kirk-Othmer Encyclopedia ofChemical Technology, Vol. 3, 3rd Edition (1978).

The potentiated sulfonamide and the ionophore are employed in thecompositions of this invention in relative proportions which aresynergistic in combating coccidiosis-producing microorganisms,particularly against those strains that have developed resistance toindividual ionophores.

The anticoccidial animal comestible compositions of this invention areprepared by mixing the active ingredients with a suitable carrier ordiluent material which is generally used in animal feeds or drinkingwater. The concentration of the active ingredients in an animalcomestible composition can be adjusted to meet particular needs and maybe varied over a wide range. The minimum concentration should be such asto achieve the desired control of coccidiosis and the maximumconcentration should be such as to avoid any undesired side effects whenthe comestible composition is ingested by the animal. Within theselimitations, specific amounts will normally be regulated by thepractitioner according to the potency and usual recommended dosing levelfor the individual active ingredients. A benefit from the potentiatinginteraction of the active ingredients is that the amount of eachcomponent required may be less then would ordinarily be necessary ifthey were used separately as a coccidiostat or anticoccidial. Thus, theamount of ionophore necessary may advantageously be reduced.

In preferred embodiments, medicated comestible compositions according tothis invention will contain the potentiated sulfonamide component inconcentrations from about 0.01 to about 0.02% by weight, with theconcentration of the ionophore component being selected accordingly toachieve the desired degree of anticoccidial results.

To illustrate, an average recommended dosing level for lasalocid inpoultry for the prevention of coccidiosis would be about 100 ppm(approved range 75-125 ppm). The compositions in accordance with thisinvention preferably contain the potentiated sulfonamide component andthe ionophore component in proportions of from about 1.5 to about 2.5parts by weight of the potentiated sulfonamide per part by weight oflasalocid, with resulting dosing levels of from about 75-125 to about100-200 ppm of the lasalocid and potentiated sulfonamide, respectively,based on a typical dosing level for the ionophore.

Other preferred ionophore dose ranges for the present invention incombination with the potentiated sulfonamide dose levels of 100 to 200ppm are as follows:

    ______________________________________                                                          Feed Dosage                                                 ______________________________________                                        Monensin            99-121  ppm                                               Salinomycin         44-66   ppm                                               Narasin             50-70   ppm                                               Maduramycin          5-7.5  ppm                                               ______________________________________                                    

In practice, the most convenient way to administer the activeingredients is to incorporate them by mixing into the animals' feed ordrinking water. Any type of feed may be used, including common dryfeeds, liquid feeds and pelleted feeds. The components can be addedindependently in the appropriate amounts necessary to achieve synergy,or they can be added in such amounts simultaneously as a mixture. Knownmethods of mixing may be utilized.

A preferred way for purposes of this invention is to prepare aconcentrated additive premix of the active ingredients, which in turncan be added to the animals' feed to form a medicated comestiblecomposition in accordance with this invention. The premix may be eitherin liquid or dry formulations. Separately formulated premixes for eachof the active components can also be used to add them to a given feedlot to obtain the medicated comestible composition. In the usual case,premixes in accordance with this invention will contain from about 5 toabout 200 grams of coccidiostat per pound of premix.

In formulating the animal comestible to contain the proper amounts ofanticoccidial for treatment, one need only calculate the amount of thecoccidiostat desired for administration to each animal, take intoaccount the amount of feed per day normally consumed by the animal,compute the proper concentration of anticoccidial needed in the feed,and add the appropriate amount of anticoccidial or of premix to the feedto achieve that concentration.

The compositions of this invention are typically effective in combatingcoccidiosis when administered to animals in feed mixes containing theanticoccidial agent combination in an amount of from about 0.02 to about0.04% by weight of the comestible (feed mix).

Other methods of administration may also be employed. For instance, thedescribed anticoccidial agent can be incorporated into tablets,drenches, boluses or capsules and dosed to the animals. The preparationof such dosage forms can be accomplished using methods well known tothose in the veterinary pharmaceutical art. These anticoccidial agentscan also be administered by incorporation into the animals' drinkingwater.

The invention is further illustrated in the following examples.

EXAMPLE 1 Anticoccidial Activity of Sulfadimethoxine/Ormetoprim andLasalocid Against E. tenella

Compositions in accordance with the present invention comprisingsulfadimethoxine, ormetoprim (the weight ratio of these two ingredientswas 5:3) and the ionophore lasalocid were evaluated against an E.tenella strain. The strain had been exposed in the field to commonlyused coccidiostats, primarily ionophores over a long period of time withresulting reduced sensitivity to them as shown by higher mortality andaverage degrees of infection when tested against recommended dosinglevels of such agents.

Two-week old broiler chickens, obtained from a commercial hatchery andkept in wire-floored, electrically heated battery brooders, were used inall studies. Ten birds, selected according to weight and sex (50% femaleand 50% male), were included in each group. The chickens were medicatedtwo days before infection and maintained on the antibiotic until thetermination of the trial, six days post-infection. UUC (uninfected,unmedicated controls) and IUC (infected, unmedicated controls) were alsoincluded in each study.

Broiler starter mash, a complete feed formula free of drugs, was used asthe basal ration. The medicated feed was prepared by adding to the basalration the desired concentration of drug or drugs. Each drug wasthoroughly mixed into the mash prior to use to provide a uniform blend.In all instances, the medicated feed was fed two days before infectionand for a total of eight consecutive days.

The infection was induced by giving to each bird 1.0 ml of a suspensioncontaining 200,000 sporulated oocysts of E. tenella, properly agitatedand suspended in sterile distilled water, which was inoculated directlyinto the crop by means of a blunt needle attached to a calibratedsyringe.

At the termination of the trials, the surviving birds were sacrificed,necropsied, and scored for gross lesions. All birds that died during theexperiments were also necropsied. Diagnosis was based on lesion locationand morphology. The readings obtained were recorded as average degree ofinfection (ADI) according to the following scoring system: 0=normal,1=slight, 2=moderate, 3=severe, 4=dead. The ADI was calculated based onthe total of individual lesion scores divided by the number of birdsscored.

In addition, weight gains (in % relative to UUC) and feed conversion(average feed consumption/average weight gain) were recorded.

The results for the E. tenella strain are shown below. In these Tables,"Feed Conv." stands for feed conversion and "Mort." stands formortality. These results demonstrate that the combinations ofsulfadimethoxine/ormetoprim and lasalocid have significantly greateractivity than either sulfadimethoxine/ormetoprim or lasalocid alone, asreflected by the lower values for average degree of infection (ADI).Superior weight gains relative to the infected unmedicated control (IUC)are also shown. Lower lesion scores as reflected in ADI values will overlonger periods of time translate into improved body weights and greaterfeed conversions.

    ______________________________________                                                   Dosage   Weight   Feed  Mort.                                      Treatment  (ppm)    Gain, %  Conv. %     ADI                                  ______________________________________                                        UUC        --       100      1.65  0     0.0                                  IUC        --       70       2.06  12.5  3.1                                  Sulfadimethoxine:                                                                        200      91       1.77  0     1.2                                  Ormetoprim (5:3)                                                              Lasalocid  125      87       1.80  0     0.8                                              75      89       1.78  5     1.7                                  Sulfadimethoxine:                                                                         200+    80       1.98  0     0.0                                  Ormetoprim (5:3)                                                                         125                                                                + Lasalocid                                                                               200+    92       1.76  0     0.1                                              75                                                                ______________________________________                                    

EXAMPLE 2 Anticoccidial Activity of Sulfadimethoxine/Ormetoorim andMonensin Against E. tenella

The procedure described in Example 1 was repeated against a field strainof E. tenella which was ionophore-resistant as a result of exposure tomonensin over a long period of time. The results show that 200+121 ppmand 200+99 ppm dose levels of the composition ofsulfadimethoxine/ormetoprim (weight ratio 5:3) and monensin resulted inlower average degree levels of infection than the corresponding amountsof either sulfadimethoxine/ormetoprim or monensin used alone.

    ______________________________________                                                   Dosage   Weight   Feed  Mort.                                      Anticoccidial                                                                            (ppm)    Gain, %  Conv. %     ADI                                  ______________________________________                                        UUC         0       100      1.74  0.0   0.0                                  IUC         0       78       2.33  20.0  2.9                                  Sulfadimethoxine:                                                                        200      89       1.93  5.0   1.6                                  Ormetoprim (5:3)                                                              Monensin   121      75       2.20  7.5   1.9                                              99      78       2.15  10.5  2.3                                  Sulfadimethoxine:                                                                         200+    74       2.24  2.5   1.3                                  Ormetoprim (5:3)                                                                         121                                                                + Monensin                                                                    Sulfadimethoxine:                                                                         200+    77       2.18  7.5   1.2                                  Ormetoprim (5:3)                                                                          99                                                                + Monensin                                                                    ______________________________________                                    

EXAMPLE 3 Anticoccidial Activity of Sulfadimethoxine/Ormetoprim andSalinomycin Against E. tenella

The procedure described in Example 1 was repeated in an evaluation ofanticoccidial activity against an ionophore-resistant field isolate ofE. tenella, with inoculation again at 200,000 sporulated oocysts perbird, but using salinomycin as the ionophore. The results are givebelow:

    ______________________________________                                                   Dosage   Weight   Feed  Mort.                                      Anticoccidial                                                                            (ppm)    Gain, %  Conv. %     ADI                                  ______________________________________                                        UUC        0        100      1.62  0.0   0.0                                  IUC        0        71       2.11  25.0  3.1                                  Sulfadimethoxine:                                                                        200      89       1.71  5.0   2.0                                  Ormetoprim (5:3)                                                              Salinomycin                                                                              60       81       2.01  5.0   2.1                                  Sulfadimethoxine:                                                                        200+     84       1.93  0.0   0.9                                  Ormetoprim (5:3)                                                                         60                                                                 + Salinomycin                                                                 ______________________________________                                    

EXAMPLE 4 Anticoccidial Activity of Sulfadimethoxine/Ormetoprim andNarasin Against E. tenella

The procedure of Example 1 was again repeated, using narasin as theionophore, with the results shown below. Again, the combination with theionophore was superior to either of the components used alone.

    ______________________________________                                                   Dosage   Weight   Feed  Mort.                                      Anticoccidial                                                                            (ppm)    Gain, %  Conv. %     ADI                                  ______________________________________                                        UUC        0        100      1.66  0.0   0.0                                  IUC        0        51       2.63  17.5  3.1                                  Sulfadimethoxine:                                                                        200      71       2.12  5.0   2.0                                  Ormetoprim (5:3)                                                              Narasin    70       56       2.53  25.0  2.8                                  Sulfadimethoxine:                                                                        200+     76       1.91  2.5   1.6                                  Ormetoprim (5:3)                                                                         70                                                                 + Narasin                                                                     ______________________________________                                    

EXAMPLE 5 Anticoccidial Activity of Sulfadimethoxine/Ormetoprim andMaduramycin Against E. tenella

Using the procedure of Example 1, an evaluation was made of theanticoccidial activity of sulfadimethoxine/ormetoprim (5:3) and theionophore maduramycin against an ionophore-resistant isolate of an E.tenella. Once again, lower average degree levels of infection resultedfrom the use of the combination.

    ______________________________________                                                   Dosage   Weight   Feed  Mort.                                      Anticoccidial                                                                            (ppm)    Gain, %  Conv. %     ADI                                  ______________________________________                                        UUC        0        100      1.69  0.0   0.0                                  IUC        0        48       2.68  30.0  3.2                                  Sulfadimethoxine:                                                                        200      72       2.17  0.0   1.8                                  Ormetoprim (5:3)                                                              Maduramycin                                                                              7        74       1.94  0.0   1.2                                  Sulfadimethoxine:                                                                        200+     83       1.87  0.0   0.3                                  Ormetoprim (5:3)                                                                         7                                                                  + Maduramycin                                                                 ______________________________________                                    

EXAMPLE 6 Anticoccidial Activity of Sulfadimethoxine/Ormetoprim andAntibiotic X-14934A Against E. tenella

The procedure of Example 1 was repeated, using polyether antibioticX-14934A as the ionophore (U.S. Pat. No. 4,510,317), with the resultsshown below.

    ______________________________________                                                   Dosage   Weight   Feed  Mort.                                      Anticoccidial                                                                            (ppm)    Gain, %  Conv. %     ADI                                  ______________________________________                                        UUC        0        100      1.71  0.0   0.0                                  IUC        0        78       2.08  13.0  3.0                                  Sulfadimethoxine:                                                                        200      91       1.84  5.0   1.9                                  Ormetoprim (5:3)                                                              Antibiotic X-14934A                                                                      15       87       1.89  13.0  2.2                                  Sulfadimethoxine:                                                                        200+     79       2.10  10.0  1.6                                  Ormetoprim (5:3)                                                              + Antibiotic X-14934A                                                                    15                                                                 ______________________________________                                    

We claim:
 1. A composition for combating coccidiosis in animals, whichcomprises sulfadimethoxine, ormetoprim and lasalocid, wherein theseingredients are present in amounts which in combination aresynergistically effective in combating at least one coccidiosis-causingstrain of Eimeria.
 2. A comestible for feeding to animals, whichcomprises an animal feed containing an anticoccidial compositioncomprising sulfadimethoxine, ormetorpim and lasalocid, wherein thecombination of sulfadimethoxine and ormetoprim is present in an amountfrom about 0.01 to about 0.02% by weight of the animal feed and thelasalocid is present in an amount which combined with thesulfadimethoxine and ormetoprim is synergistically effective incombating at least one coccidiosis-causing strain of Eimeria.
 3. Ananimal feed additive premix containing an anticoccidial compositioncomprising sulfadimethoxine, ormetoprim and lasalocid, wherein thecombination of sulfadimethoxine and ormetoprim is present in an amountfrom about 0.01 to 0.02% by weight of the animal feed and the lasalocidis present in an amount which combined with the sulfadimethoxine andormetoprim is synergistically effective in combating at least onecoccidiosis-causing strain of Eimeria.
 4. A method of combatingcoccidiosis in animals, comprising orally administering to said animalsa prophylactic or therapeutic amount of an anticoccidial compositioncomprising sulfadimethoxine, ormetoprim and lasalocid in amounts whichin combination are synergistically effective in combating at least onecoccidiosis-causing strain of Eimeria.